KEY TAKEAWAYS

It’s well known that when you smoke — or breathe in someone else’s smoke — you raise your risk for lung cancer. But what many people don’t realize is that secondhand smoke from cigarettes can also seriously damage your heart.

One of every four Americans will die of heart disease, according to the Centers for Disease Control and Prevention (CDC), making heart disease the No. 1 killer in the United States, for men and for women.

With that in mind, consider that tobacco use is the top preventable cause of death among Americans, the CDC says. That’s true whether you smoke, or are exposed to secondhand smoke because you live or work with smokers, says R. William Vandivier, MD, a pulmonologist at the University of Colorado Hospital in Aurora. “There is no safe level of cigarette smoke, even if it is secondhand,” he says.

“There’s nothing good that’s happening when you are in the company of smokers,” says Prediman K. Shah, MD, director of the Atherosclerosis Prevention and Treatment Center and the Oppenheimer Atherosclerosis Research Center at Cedars-Sinai Medical Center in Los Angeles.

According to the CDC, exposure to tobacco smoke increases a nonsmoker’s risk for heart disease by 25 to 30 percent.

The Secondhand Smoke Effect on Your Heart

When the toxins in smoke get into your system, they damage the lining of your blood vessels, says Suzanne Steinbaum, DO, a cardiologist at the Lenox Hill Hospital and Vascular Institute of New York. The damage allows plaque to build up along the vessel walls. Your blood vessels become narrow and stiff, and blood can’t flow properly.

Exposure to tobacco smoke increases a nonsmoker’s risk for heart disease by 25 to 30 percent.

This can lead to a heart attack, according to the National Heart, Lung, and Blood Institute. Plaque can break off and block the blood supply to your brain, which can cause a stroke, the organization says. Another danger of plaque is that it can also build up in the vessels that carry blood to your limbs, leading to peripheral artery disease, which can cause pain and numbness. And, when your heart works harder to deliver blood to your body, your blood pressure rises.

Smoke can also affect your cholesterol. The CDC says that smoke can raise your triglycerides, a type of fat in your blood, lowering your good cholesterol (HDL). When doctors assess patients for heart disease, they must look at all their risk factors, and having high blood fat and cholesterol levels is one, Dr. Steinbaum says.

Nancy Ann Rigotti, MD, director of the Tobacco Treatment and Research Center at Massachusetts General Hospital, points out another danger: When a cigarette burns, it produces carbon monoxide (CO). Red blood cells absorb CO much faster than they absorb oxygen. As a result, CO binds to blood cells meant to carry oxygen, and your heart has to work harder to do its job.

Actually, any tobacco smoke is too much, Rigotti says, because "it doesn’t take a lot of exposure to cause effects in your blood."

Speak Up About Secondhand Smoke

Most doctors routinely ask patients if they smoke. But they don't always ask if their patients live or work around smokers. Dr. Rigotti and colleague Sandra J. Japuntich, PhD, confirmed this with a study. They asked patients hospitalized with heart disease: Have you been asked if you have been around smokers? Fewer than 18 percent said yes. Their findings were published in JAMA Internal Medicine in November 2014.

If you live with a smoker or work with smokers, you should tell your cardiologist up front, even if you're not asked, Steinbaum says. Your cardiologist will look at all your risk factors for heart disease, she says. And if you spend time around smokers and have other risk factors, the doctor may want to treat you more aggressively.

As Dr. Vandivier says, “If you tell your doctors, they can be of more help to you."

Protect Yourself From Secondhand Smoke

Tell your doctor if you live or work with smokers. And consider these steps to limit your smoke exposure:

Ask those who smoke at home or work to go outside. Talk to your boss if your colleagues give you a rough time about this, Vandivier says.

If you live in a multi-unit building, Rigotti suggests talking to your landlord about banning smoking throughout. Smoke can waft from one apartment to another.

Don’t allow anyone to smoke in your car. A car is a confined space and that makes exposure worse, Vandivier says.

Avoid bars and restaurants where smoking is allowed, and other places where you’re likely to encounter smoke, Vandivier suggests.

If someone lights up near you, Steinbaum says to ask the person to move away — and leave if the person doesn't.